It has been suggested that HLA restriction may play a significant role in the development of immunity through vaccine administration. Current efforts focus on the HLA class I alleles and peptide vaccines, and on the prediction of levels of favorable response in 15 ethnic groups, based upon population genetic models and known allele and haplotype frequencies for class I HLA loci. Estimates of coverage probabilities have been obtained based upon these frequencies, and the probable number of alleles needed to achieve such coverage has been obtained based upon individual populations, racial groupings, and all fifteen ethnic groups.[unreadable]